Diagnostic Test

WARNING: This page is about a different car, the 2013 RAM 2500 HD and 2012 RAM Pickup. However, it is still accessible from the selected car via links, so may be relevant.

CHECK THE HIGH SIDE PRESSURE
1. Start the engine.
2. With the scan tool, navigate to Systems Tests and select forced CNG fuel mode on.
3. With the scan tool, view the pressure reading for the CNG Tank Pressure Sensor.
  NOTE:
  The high side system pressure must be above approximately 250 psi for the system to operate.
  
  Is the pressure high enough for the system to operate?
  
  Yes
  - Go To 2
  No
  - Verify that there is sufficient fuel in the CNG Tanks. If tanks have sufficient fuel, perform the appropriate repair in the high pressure system in accordance with the service information.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to STANDARD PROCEDURE .
LOW PRESSURE FUEL SYSTEM LEAK
1. Check the low pressure side of the system for leaks using soapy water.
  Were any leaks found?
  
  Yes
  - Perform the appropriate repair in accordance with the service information.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to STANDARD PROCEDURE .
  No
  - Go To 3
HIGH RESISTANCE IN THE CNG RAIL PRESSURE SENSOR CIRCUITS
1. Turn the ignition off.
2. Disconnect the Fuel Rail Sensor harness connector.
3. Disconnect the PCM C2 harness connector.
  CAUTION:
  Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install the GPEC Diagnostic Adaptor to perform the diagnosis.
4. Connect the (special tool #10436, Adapter, GPEC Diagnostic).
5. Measure the resistance of the:
  - (K162) CNG Rail Pressure Sensor circuit between the Fuel Rail Sensor harness connector and the GPEC Adaptor.
  - (K900) Sensor Return circuit between the Fuel Rail Sensor harness connector and the GPEC Adaptor.
  Is the resistance below 5.0 Ohms for both circuits?
  
  Yes
  - Go To 4
  No
  - Repair the circuit that measured above 5.0 Ohms.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to STANDARD PROCEDURE .
CNG RAIL SENSOR
1. Replace the CNG Rail Sensor in accordance with the service information.
2. Reconnect the PCM C2 harness connector.
3. Turn the ignition on.
4. With the scan tool, erase DTCs.
5. Start the engine and test drive the vehicle in CNG fuel mode.
6. With the scan tool, view DTCs
  Did the DTC return?
  
  Yes
  - Go To 5
  No
  - Repair is complete.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to STANDARD PROCEDURE .
CNG PRESSURE REGULATOR
1. Replace the CNG Pressure Regulator in accordance with the service information.
2. Turn the ignition on.
3. With the scan tool, erase DTCs.
4. Start the engine and test drive the vehicle in CNG fuel mode.
5. With the scan tool, view DTCs
  Did the DTC return?
  
  Yes
  - Go To 6
  No
  - Repair is complete.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to STANDARD PROCEDURE .
POWERTRAIN CONTROL MODULE (PCM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the CNG Rail Sensor and the Powertrain Control Module (PCM).
2. Look for any chafed, pierced, pinched, or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals.
4. Monitor the scan tool data relative to this circuit and wiggle test the wiring and connectors.
5. Look for the data to change or for the DTC to reset during the wiggle test.
6. Perform any Technical Service Bulletins that may apply.
  Were any problems found?
  
  Yes
  - Repair as necessary.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to STANDARD PROCEDURE .
  No
  - Replace and program the Powertrain Control Module (PCM) in accordance with the service information. Refer to MODULE, POWERTRAIN CONTROL, REMOVAL .
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to STANDARD PROCEDURE .